Stool Microbiota Diversity Analysis of Blastocystis-Positive and Blastocystis-Negative Individuals

Intestinal Blastocystis is linked to healthier diets and more favorable cardiometabolic outcomes in 56,989 individuals from 32 countries

Diet impacts human health, influencing body adiposity and the risk of developing cardiometabolic diseases. The gut microbiome is a key player in the diet-health axis, but while its bacterial fraction is widely studied, the role of micro-eukaryotes, including Blastocystis, is underexplored. We performed a global-scale analysis on 56,989 metagenomes and showed that human Blastocystis exhibits distinct prevalence patterns linked to geography, lifestyle, and dietary habits. Blastocystis presence defined a specific bacterial signature and was positively associated with more favorable cardiometabolic profiles and negatively with obesity (p < 1e-16) and disorders linked to altered gut ecology (p < 1e-8). In a diet intervention study involving 1,124 individuals, improvements in dietary quality were linked to weight loss and increases in Blastocystis prevalence (p = 0.003) and abundance (p < 1e-7). Our findings suggest a potentially beneficial role for Blastocystis, which may help explain personalized host responses to diet and downstream disease etiopathogenesis.

A mitochondrial carrier transports glycolytic intermediates to link cytosolic and mitochondrial glycolysis in the human gut parasite Blastocystis

Stramenopiles form a clade of diverse eukaryotic organisms, including multicellular algae, the fish and plant pathogenic oomycetes, such as the potato blight Phytophthora, and the human intestinal protozoan Blastocystis. In most eukaryotes, glycolysis is a strictly cytosolic metabolic pathway that converts glucose to pyruvate, resulting in the production of NADH and ATP (Adenosine triphosphate). In contrast, stramenopiles have a branched glycolysis in which the enzymes of the pay-off phase are located in both the cytosol and the mitochondrial matrix. Here, we identify a mitochondrial carrier in Blastocystis that can transport glycolytic intermediates, such as dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, across the mitochondrial inner membrane, linking the cytosolic and mitochondrial branches of glycolysis. Comparative analyses with the phylogenetically related human mitochondrial oxoglutarate carrier (SLC25A11) and dicarboxylate carrier (SLC25A10) show that the glycolytic intermediate carrier has lost its ability to transport the canonical substrates malate and oxoglutarate. Blastocystis lacks several key components of oxidative phosphorylation required for the generation of mitochondrial ATP, such as complexes III and IV, ATP synthase, and ADP/ATP carriers. The presence of the glycolytic pay-off phase in the mitochondrial matrix generates ATP, which powers energy-requiring processes, such as macromolecular synthesis, as well as NADH, used by mitochondrial complex I to generate a proton motive force to drive the import of proteins and molecules. Given its unique substrate specificity and central role in carbon and energy metabolism, the carrier for glycolytic intermediates identified here represents a specific drug and pesticide target against stramenopile pathogens, which are of great economic importance.

Molecular detection of intestinal parasites in a rural community of Colombia: A one health approach to explore potential environmental-zoonotic transmission

AIMS

Protozoan and helminth parasitic infections pose significant public health challenges, especially in developing countries with rural populations marked by suboptimal hygiene practices and socio-economic constraints. The parasites are the etiological agents of these infections and have a notably elevated global prevalence. Therefore, this study focuses on estimating the frequency and transmission dynamics of several parasitic species, including Blastocystis, Giardia, Cryptosporidium spp., Entamoeba histolytica, Ascaris lumbricoides, Trichuris trichiura, Taenia spp. and hookworms, within a rural community in southwest Colombia with a particular emphasis on the One Health framework, considering environmental and zoonotic transmission potentials.

METHODS AND RESULTS

This study involved the analysis of 125 samples, encompassing human participants (n = 99), their domestic pets (dogs) (n = 24) and water sources (n = 2). Parasite detection was carried out utilizing a combination of microscopy and molecular techniques. Furthermore, the characterization of Blastocystis subtypes (STs) was achieved through Oxford Nanopore sequencing of the rRNA-18S gene. The investigation also entailed the examination of potential associations between intestinal parasitism and various sociodemographic factors. Results revealed a high frequency of parasitic infections when employing molecular methods, with Blastocystis (n = 109/87%), Giardia (n = 20/16%), Ancylostoma duodenale (n = 28/22%), Ancylostoma ceylanicum (n = 7/5.6%), E. histolytica (n = 6/4.8%), Cryptosporidium spp. (n = 12/9.6%) and even Taenia (n = 1/0.8%) detected. Cryptosporidium spp. was also identified in water samples. Coinfections were prevalent, with 57% (n = 70) of samples exhibiting single-parasite infections and 43% (n = 53) showing various degrees of polyparasitism, emphasizing the complexity of transmission dynamics. Blastocystis subtyping, conducted via Oxford Nanopore sequencing, revealed a diversity of subtypes and coexistence patterns, with ST2 being the most prevalent.

CONCLUSIONS

This research underscores the importance of using molecular techniques for frequency estimation, particularly emphasizing the relevance of zoonotic transmission in parasitic infections. It highlights the significance of the One Health approach in comprehending the circulation of parasites among animals, humans and environmental sources, thereby directly impacting public health and epidemiological surveillance.

The influence of plant extracts on viability of ST3 and ST7 subtypes of Blastocystis sp

Blastocystis sp. is one of the most frequently detected protozoa during stool specimen examination. In the last decade, the studies about the pathogenic potential of Blastocystis sp. have intensified. Additionally, treatment approaches against this parasite are still disputable. The study aimed to investigate the in vitro activity of the substances of natural origin against two subtypes (ST) of Blastocystis sp.-ST3 and ST7. Garlic and turmeric extracts exhibited the highest inhibitory effect in relation to the ST3 viability. While horseradish and turmeric were found to be the most effective extracts to the ST7 viability. The study showed that ginger, garlic, horseradish, and turmeric extracts have potent antimicrobial activity against Blastocystis ST3 and ST7, with the half-maximal inhibitory concentration (IC50) ranging from 3.8 to 4.8 µg/ml and from 3.3 to 72.0 µg/ml, respectively, and thus may be useful in the prevention and control of Blastocystis infections. Additionally, this research confirmed that Blastocystis ST7 is more resistant to the selected plant extracts treatment than Blastocystis ST3 which in consequence may bring some difficulties in its eradication.

Prevalence and genetic diversity of Blastocystis sp. among autochthonous and immigrant patients in Italy

The prevalence of Blastocystis sp., its genetic diversity and the distribution of circulating subtypes (STs) were molecularly investigated in a cohort of autochthonous and immigrant patients with gastrointestinal symptoms hospitalized over the period February 2022-June 2023 at the Policlinico Ospedaliero-Universitario "Riuniti", Foggia, in Southern Italy. The population variables, including patient geographical origin, gender and age classes were reported. Out of the 927 investigated patients, 36 (3.9%) were positive for Blastocystis sp. A statistically significant association with African origin and age classes >18 years old was found. ST1 (allele 4), ST2 (alleles 9, 13), ST3 (alleles 34, 36) and ST4 (allele 92) were the subtypes detected with a different distribution between autochthonous and immigrant patients. Co-infections with enteric protozoa such as Giardia duodenalis and Dientamoeba fragilis, pathogenic bacteria as Clostridioides difficile, Campylobacter jejuni and Aeromonas sp. and viral infections such as Norovirus were found in 33% of cases. This is the first study of Blastocystis sp., its circulating subtypes and allele variability among patients with different geographical origin in an area of Southern Italy, in the Central Mediterranean, characterized by high immigrant pressure. These results provide baseline data to better investigate a potential interaction between Blastocystis sp. and other risk factors in patients with gastrointestinal symptoms.

Profiling of the fecal microbiota and circulating microRNA-16 in IBS subjects with Blastocystis infection : a case-control study

Irritable bowel syndrome (IBS) is a prevalent gastrointestinal (GI) tract disorder. Although the main reason for IBS is not clear, the interaction between intestinal microorganisms and the gut barrier seems to play an important role in pathogenesis of IBS. The current study aimed to investigate the effect of Blastocystis on the gut microbiota profile and the circulation levels of microRNA (mir)-16 of IBS patients compared to healthy subjects. Stool and blood samples were collected from 80 participants including 40 samples from each IBS and healthy group. Upon DNA extraction from stool samples, barcoding region and quantitative real-time PCR were analyzed to investigate Blastocystis and the microbiota profile, respectively. RNA was extracted from serum samples of included subjects and the expression of mir-16 was evaluated using stem-loop protocol and qreal-time PCR. Significant changes between IBS patients and healthy controls was observed in Firmicutes, Actinobacteria, Faecalibacterium, and Alistipes. In IBS patients, the relative abundance of Bifidobacteria was directly correlated with the presence of Blastocystis, while Alistipes was decreased with Blastocystis. Lactobacillus was significantly increased in Blastocystis carriers. In healthy subjects, the relative abundance of Bifidobacteria was decreased, but Alistipes was increased in Blastocystis carriers. The changes in the Firmicutes/Bacteroidetes ratio was not significant in different groups. The relative expression of mir-16 in Blastocystis-negative IBS patients and healthy carriers was significantly overexpressed compared to control group. The presence of Blastocystis, decreased the relative expression of mir-16 in IBS patients compared to Blastocystis-negative IBS patients. The present study revealed that Blastocystis has the ability to change the abundance of some phyla/genera of bacteria in IBS and healthy subjects. Moreover, Blastocystis seems to  modulate the relative expression of microRNAs  to control the gut atmosphere, apply its pathogenicity, and provide a favor niche for its colonization.

Molecular characterization of Blastocystis and Entamoeba of muskoxen and sheep in Greenland

Molecular characterisation of endobionts that are shared among human and non-human hosts can help shed light on the epidemiology and inform studies that aim to unravel the role of these organisms in health and disease. Two of the most common of shared endobionts include the single-celled intestinal protists Blastocystis and Entamoeba. Here, we present the first known data on genetic diversity and host specificity of these two genera in Greenland. Faecal DNA samples from 243 muskoxen and 44 sheep were submitted to metabarcoding of nuclear small subunit ribosomal DNA. Entamoeba- and Blastocystis-specific sequences were clustered, and consensus sequences were subjected to taxonomic query. Using MinION-based sequencing, near-complete nuclear small subunit ribosomal DNA sequences were obtained from four faecal samples. Of the 243 muskox samples, 180 (74%) and 19 (8%) were positive for Blastocystis and Entamoeba, respectively. Forty (91%) and six (14%) of the 44 sheep samples were positive for Blastocystis and Entamoeba, respectively. Blastocystis subtypes (ST) 10, 14, 21, 24-26, and a novel subtype (ST40) were identified. Colonisation by more than one subtype was common. ST40 was common in muskoxen but limited to Northeast Greenland. Entamoeba bovis and the E. bovis-associated ribosomal lineages (RL) 1 and 8 were found, and three conditional lineages (CL) 3, 4, and 10 were confirmed; CL10 was promoted to RL12. Several novel lineages were identified, all of which were linked to the E. bovis complex. In conclusion, Blastocystis was far more common than Entamoeba and found in approximately three of every four animals; both can be considered common colonisers of large herbivorous mammals in Greenland. Multiple subtypes/lineages of both genera were commonly observed, some of which were novel, but most of which are seen in many other parts of the world.

Distribution of Blastocystis subtypes isolated from various animal hosts in Thailand

Blastocystis is a parasitic protist of a variety of hosts, including humans. Mapping the distribution of Blastocystis and its genetic variants across different host species can help us understand the epidemiology of this organism and its role in health and disease. This study aimed to identify subtypes of Blastocystis detected in different animal hosts in Thailand. A total of 825 fecal samples belonging to 18 vertebrate orders, 36 families, 68 genera, and 80 species were collected. Of these, 111 specimens were Blastocystis-positive by culture. Seventy-nine samples were subjected to small subunit (SSU) ribosomal DNA amplification by PCR, and reliable subtype data were obtained for 61 specimens. At least 14 subtypes (ST), namely ST1 to ST10, ST14/ST24/ST25 complex, ST23, ST26, and ST29 were detected. In addition, Blastocystis was found in tortoises. ST1 (3.2%) and ST5 (11.5%) were found in pigs, ST2 (1.6%) and ST3 (3.2%) in non-human primates, ST4 (14.7%) in rodents and ruminants, ST6 (4.9%), ST7 (30%), ST9 (1.6%), and ST29 (1.6%) in birds, ST8 (6.6%) in Green peafowl and East Asian Porcupine, and ST10 (4.9%), ST14/ST24/ST25 (9.8%), ST23 (1.6%) and ST26 (1.6%) in ruminants. The sequence recovered from the elongated tortoises (Indotestudo elongata) (3.2%) was phylogenetically placed within the reptilian cluster of Blastocystis, for which no subtype system is available yet. Of note, we did not obtain Blastocystis sequences from any of the many canids and felids sampled in the study, and our data are in support of host specificity of Blastocystis, according to both colonization and subtype distribution.

Differential gut microbiome in spondyloarthritis patients associated to Blastocystis colonization

The role of Blastocystis in intestinal health is an open controversy, and little is known about the potential effect of this microorganism in autoinflammatory diseases such as spondyloarthritis (SpA). Here, we analyzed the gut microbiome of 36 SpA patients and 13 control individuals and demonstrated that the richness, diversity, and taxonomic composition between these two groups are different. We also showed that colonization by Blastocystis in control individuals increases the richness and diversity of the intestinal microbiome, whereas in SpA patients, it does not seem to have any impact. This may reflect a potential role of Blastocystis in sculpting the gut microbiome architecture in control individuals, whereas in subjects with SpA, the modulation of the microbiome may be governed by disease-dependent factors that cannot be overcome by Blastocystis. Regarding taxonomic characterization, SpA patients colonized by Blastocystis showed significant increases in the phylum Pseudomonadota, class Gammaproteobacteria, family Succinivibrionaceae, and genus Succinivibrio. Simultaneously, there were significant increases in the class Bacilli, order Lactobacillales, families Lactobacillaceae and Clostridiaceae, and genera Lactobacillus and Clostridium in non-colonized SpA patients. On the other hand, PICRUSt analysis in Blastocystis-positive SpA patients showed elevations in pathways that may enhance antioxidant capacities and alleviate intestinal inflammation, while Blastocystis-negative SpA patients showed significant changes in pathways that promote cell division/proliferation and can lead to larger changes in the gut microbiome. Our analyses lead us to believe that these changes in the gut microbiome of SpA patients may trigger protective mechanisms as an initial response to inflammation in an attempt to restore balance in the intestinal environment.

Microbiota and parasite relationship

The diversity of microbiota is different in each person. Many health problems such as autoimmune diseases, diabetes, cardiovascular diseases, and depression can be caused by microbiota imbalance. Since the parasite needs a host to survive, it interacts closely with the microbiota elements. Blastocystis acts on the inflammatory state of the intestine and may cause various gastrointestinal symptoms, on the contrary, it is more important for gut health because it causes bacterial diversity and richness. Blastocystis is associated with changes in gut microbiota composition, the ultimate indicator of which is the Firmicutes/Bacteroidetes ratio. The Bifidobacterium genus was significantly reduced in IBS patients and Blastocystis, and there is a significant decrease in Faecalibacterium prausnitzii, which has anti-inflammatory properties in Blastocystis infection without IBS. Lactobacillus species reduce the presence of Giardia, and the produced bacteriocins prevent parasite adhesion. The presence of helminths has been strongly associated with the transition from Bacteroidetes to Firmicutes and Clostridia. Contrary to Ascaris, alpha diversity in the intestinal microbiota decreases in chronic Trichuris muris infection, and growth and nutrient metabolism efficiency can be suppressed. Helminth infections indirectly affect mood and behavior in children through their effects on microbiota change. The main and focus of this review is to address the relationship of parasites with microbiota elements and to review the data about what changes they cause. Microbiota studies have gained importance recently and it is thought that it will contribute to the treatment of many diseases as well as in the fight against parasitic diseases in the future.

Colonization with ubiquitous protist Blastocystis ST1 ameliorates DSS-induced colitis and promotes beneficial microbiota and immune outcomes

Blastocystis is a species complex that exhibits extensive genetic diversity, evidenced by its classification into several genetically distinct subtypes (ST). Although several studies have shown the relationships between a specific subtype and gut microbiota, there is no study to show the effect of the ubiquitous Blastocystis ST1 on the gut microbiota and host health. Here, we show that Blastocystis ST1 colonization increased the proportion of beneficial bacteria Alloprevotella and Akkermansia, and induced Th2 and Treg cell responses in normal healthy mice. ST1-colonized mice showed decreases in the severity of DSS-induced colitis when compared to non-colonized mice. Furthermore, mice transplanted with ST1-altered gut microbiota were refractory to dextran sulfate sodium (DSS)-induced colitis via induction of Treg cells and elevated short-chain fat acid (SCFA) production. Our results suggest that colonization with Blastocystis ST1, one of the most common subtypes in humans, exerts beneficial effects on host health through modulating the gut microbiota and adaptive immune responses.

Molecular epidemiology and subtyping of Blastocystis sp. and its subtypes in celiac patients; a case control study

Blastocystis sp. is a common intestinal protist, reported from symptomatic and asymptomatic subjects. Blastocystis sp. has been reported from a broad spectrum of gastrointestinal disorders. Celiac disease (CD) is an autoimmune disorder of the small intestine, which leads to the lack of tolerance against gluten. Long-term following of gluten-free diet in CD patients decreases the gut microbiota restoration and probably decreases the chance of Blastocystis sp. colonization. The current study aimed to investigate the prevalence of Blastocystis sp. and its subtypes in CD patients in comparison to healthy subjects. Stool samples were collected from 238 participants including 92 confirmed CD patients and 146 healthy subjects. upon DNA extraction, the presence of Blastocystis sp. was evaluated using amplification of discriminative regions of the small ribosomal RNA (ssu rRNA) gene. To characterize subtypes and alleles, amplified fragments were sequenced. Phylogenetic trees were constructed to visualize subtype correlation. Our findings showed that 21% (50) of samples including 16.3% (15/92) and 23.97% (35/146) were positive for Blastocystis sp. in CD patients and healthy controls, respectively. Except family relationship, other variables were not statistical correlated with the presence of Blastocystis sp.. Totally, 25 samples were successfully sequenced. Accordingly, ST1, ST2, and ST3 were present in 8 (32%), 9 (36%), and 8 (32%) of the samples, respectively. Allele discrimination showed that all ST1 were allele 4; alleles 11, 9, and 12 were retrieved from ST2, and alleles 34, 36, and 38 were observed in ST3. The relationship between colonization of Blastocystis sp. and alteration in the gut microbiota composition is indeterminate, however, this hypothesis that lower prevalence of Blastocystis sp. in CD patients who follow a gluten-free diet affect the colonization of Blastocystis sp. via alteration in the gut microbiota composition could be interesting for further investigations.

Further insight into the genetic diversity of Entamoeba coli and Entamoeba hartmanni

Despite the species' wide distribution, studies of the genetic diversity within Entamoeba coli and Entamoeba hartmanni remain limited. In the present study, we provide further insight into the genetic diversity of both species based on analysis of partial nuclear small subunit ribosomal DNA sequences generated from human fecal DNAs from samples collected in Africa, South America, and Europe. Reinforcing the previous recognition that E. coli is a species complex, our data confirm the existence of the two subtypes, ST1 and ST2, previously identified plus, potentially, a new subtype, ST3. While ST1 appears to be genetically quite homogenous, ST2 shows a substantial degree of intrasubtype diversity. ST2 was more common in samples collected outside Europe, whereas ST1 showed no geographical restriction. The potentially novel subtype is represented to date exclusively by sequences from South American and African samples. In contrast to previous reports, our new data also indicate substantial variation in E. hartmanni that could also support the establishment of subtypes within this species. Here, however, no links were identified between subtype and geographical origin.

Prevalence and temporal dynamics of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. among toddlers attending day-care centres in Spain. A prospective molecular-based longitudinal study

Giardia duodenalis, Cryptosporidium spp., and Blastocystis sp. are common intestinal eukaryotic parasites affecting children in developed and resource-limited countries. Lack of information on the epidemiology and long-term stability in asymptomatic children complicates interpretation of transmission and pathogenesis. To assess the occurrence, genetic diversity, and temporal dynamics of intestinal eukaryotic parasites in young children, 679 stool samples from 125 toddlers attending six public day-care centres in Central Spain were collected bimonthly within a 1-year period. Detection and identification of species/genotypes were based on PCR and Sanger sequencing methods. Four eukaryotic species were identified: G. duodenalis (2.5‒31.6%), Cryptosporidium spp. (0.0‒2.4%), Blastocystis sp. (2.5‒6.4%), and Entamoeba dispar (0.0‒0.9%). Entamoeba histolytica and Enterocytozoon bieneusi were undetected. Sequence analyses identified assemblage A (63.6%) and B (36.4%) within G. duodenalis (n = 11), C. hominis (40%), C. parvum (40%), and C. wrairi (20%) within Cryptosporidium spp. (n = 5), and ST1 (3.8%), ST2 (46.2%), ST3 (15.4%), and ST4 (34.6%) within Blastocystis sp. (n = 26). Giardia duodenalis sub-assemblage AII/AIII was detected in a toddler for 10 consecutive months. Stable carriage of Blastocystis ST2 allele 9, ST3 allele 34, and ST4 allele 42 was demonstrated in five toddlers for up to 1 year.   Conclusions: Giardia duodenalis and Blastocystis sp. were common in toddlers attending day-care centres in Central Spain. Long-term infection/colonization periods by the same genetic variant were observed for G. duodenalis (up to 10 months) and Blastocystis sp. (up to 12 months). What is Known: • Asymptomatic carriage of G. duodenalis and Blastocystis sp. is frequent in toddlers. • The epidemiology and long-term stability of these eukaryotes in asymptomatic young children is poorly understood. What is New: • Long-term colonization/infection periods by the same genetic variant were described for Blastocystis sp. (up to 12 months) and G. duodenalis (up to 10 months).

Colonization with two different Blastocystis subtypes in DSS-induced colitis mice is associated with strikingly different microbiome and pathological features

Rationale: The gut microbiota plays a significant role in the pathogenesis of inflammatory bowel disease (IBD). However, the role of Blastocystis infection and Blastocystis-altered gut microbiota in the development of inflammatory diseases and their underlying mechanisms are not well understood. Methods: We investigated the effect of Blastocystis ST4 and ST7 infection on the intestinal microbiota, metabolism, and host immune responses, and then explored the role of Blastocystis-altered gut microbiome in the development of dextran sulfate sodium (DSS)-induced colitis in mice. Results: This study showed that prior colonization with ST4 conferred protection from DSS-induced colitis through elevating the abundance of beneficial bacteria, short-chain fatty acid (SCFA) production and the proportion of Foxp3⁺ and IL-10-producing CD4⁺ T cells. Conversely, prior ST7 infection exacerbated the severity of colitis by increasing the proportion of pathogenic bacteria and inducing pro-inflammatory IL-17A and TNF-α-producing CD4⁺ T cells. Furthermore, transplantation of ST4- and ST7-altered microbiota resulted in similar phenotypes. Conclusions: Our data showed that ST4 and ST7 infection exert strikingly differential effects on the gut microbiota, and these could influence the susceptibility to colitis. ST4 colonization prevented DSS-induced colitis in mice and may be considered as a novel therapeutic strategy against immunological diseases in the future, while ST7 infection is a potential risk factor for the development of experimentally induced colitis that warrants attention.

Infection with pathogenic Blastocystis ST7 is associated with decreased bacterial diversity and altered gut microbiome profiles in diarrheal patients

Background

Blastocystis is a common protistan parasite inhabiting the gastrointestinal tract of humans and animals. While there are increasing reports characterizing the associations between Blastocystis and the gut microbiome in healthy individuals, only a few studies have investigated the relationships between Blastocystis and the gut microbiota in diarrheal patients.

Methods

The effects of a specific subtype (ST7) of Blastocystis on the composition of gut microbiota in diarrheal patients were investigated using 16S ribosomal RNA (rRNA) gene sequencing and bioinformatic analyses.

Results

Compared with diarrheal patients without Blastocystis, diarrheal patients infected with Blastocystis ST7 exhibited lower bacterial diversity. Beta diversity analysis revealed significant differences in bacterial community structure between ST7-infected and Blastocystis-free patients. The proportion of Enterobacteriaceae and Escherichia-Shigella were significantly enriched in ST7-infected patients. In contrast, the abundance of Bacteroides and Parabacteroides were more prevalent in Blastocystis-free patients.

Conclusions

The results of this study revealed, for the first time, that infection with Blastocystis ST7 is associated with lower bacterial diversity and altered microbial structure in diarrheal patients. Our study on clinical diarrheal patients is also the first to reinforce the notion that ST7 is a pathogenic subtype of Blastocystis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05435-z.

The regulatory function of Blastocystis spp. on the immune inflammatory response in the gut microbiome

Blastocystis spp. is a unicellular organism that resides in digestive tract of various vertebrates, with a worldwide distribution and a variable prevalence. For many years, Blastocystis spp. was considered a cyst of a flagellate, a fungus, or a saprophyte yeast of the digestive tract; in 1996, it is placed in the group of stramenopiles (heterokonts). Since its new classification, many questions have arisen around this protist about its role as a pathogen or non-pathogen organism. Recent evidence indicates that Blastocystis spp. participates in the immune inflammatory response in the intestinal microbiome generating an anti-inflammatory response, showing a lower concentration of fecal inflammatory markers in infected human hosts. Here, we review recent findings on the regulatory function of Blastocystis spp. in the immune inflammatory response to comprehend the purpose of Blastocystis spp. in health and disease, defining if Blastocystis spp. is really a pathogen, a commensal or even a mutualist in the human gut microbiome.

Gut Microbiota Shifting in Irritable Bowel Syndrome: The Mysterious Role of Blastocystis sp

Irritable bowel syndrome (IBS) is a chronic disorder, which its causative agent is not completely clear; however, the interaction between microorganisms and gastrointestinal (GI) epithelial cells plays a critical role in the development of IBS and presenting symptoms. During recent decades, many studies have highlighted the high prevalence of Blastocystis sp. in patients with IBS and suggested a probable role for this protist in this disease. Recent studies have documented changes in the gut microbiota composition in patients with IBS regarding the presence of Blastocystis sp., but it is not clear that either disturbance of the gut during GI disorders is a favorable condition for Blastocystis sp. colonization or the presence of this protist may lead to alteration in the gut microbiota in IBS patients. In this review, we comprehensively gather and discuss scientific findings covering the role of Blastocystis sp. in IBS via gut microbiota shifting.

Alteration of gut bacteria composition among individuals with asymptomatic Blastocystis infection: A case-control study

The gut microbiota consists a diverse and complex ecosystem that is involved in beneficial functions as well as potentially harmful conditions for human. Blastocystis sp. is a common parasite of the digestive tract of animals and humans; however, limited data is available concerning the association of asymptomatic Blastocystis infection and gut bacteria composition. Hence, in this cross-sectional study, the gut bacteria composition of twenty asymptomatic Blastocystis sp. positive and twenty Blastocystis sp. negative individuals was assessed with real time PCR. The case and control groups were matched for age and sex. Both groups were negative for other gastrointestinal infections and did not have any gastrointestinal symptoms. The subtype of ten Blastocystis sp. isolates was assessed based on sequencing. Sequencing of ten Blastocystis sp. isolates revealed the ST1, ST2, and ST3 subtypes in 40%, 30%, and 30% of the isolates. The relative expression of each bacteria in the case than control group revealed that the expression level of Bifidobacterium group (P < 0.033), Peptostreptococcus productus (P < 0.014), Lactobacillus/Enterococcus group (P < 0.001), and Escherichia coli (P < 0.001) were significantly upregulate in the Blastocystis sp. carriers than the control group, while the relative amounts of Bacteroides fragilis (P < 0.001) and Enterococcus sp. (P < 0.001) were significantly downregulated in the case than the control group. Taken together, the results of this study have shown that asymptomatic Blastocystis infection could alter the composition of gut bacteria in healthy individuals.

Echinococcosis Is Associated with the Increased Prevalence of Intestinal Blastocystis Infection in Tibetans and Host Susceptibility to the Blastocystis in Mice

Blastocystis is a common human intestinal protozoan parasite. Little is known about its prevalence in echinococcosis. This study tested whether Echinococcus multilocularis infection would increase host susceptibility to Blastocystis. A total of 114 fecal samples (68 hydatid disease patients and 46 healthy people) were collected from Tibetans in the Qinghai province in China. The presence of Blastocystis was identified by sequencing of the small subunit (SSU) rRNA gene. Balb/c mice were co-infected with Blastocystis and E. multilocularis and tested for host susceptibility to Blastocystis. The overall Blastocystis prevalence was 12.3%; 16.2% in the patients and 4.4% in healthy people (p < 0.05). Sequence analysis identified three known Blastocystis genotypes, including ST1, ST2, and ST3, and one unknown genotype. Experimental dual infection significantly reduced mouse survival rate (20%), induced more severe signs, and increased intestinal damages with a higher intestinal colonization level of Blastocystis. The mouse model showed that E. multilocularis infection increases host susceptibility to Blastocystis. Our study shows a significantly higher prevalence of Blastocystis in patients with liver echinococcosis and reveals that non-intestinal E. multilocularis infection increases host susceptibility to the Blastocystis. Our results highlight that E. multilocularis infection is associated with Blastocystis. These findings remind us that more attention should be paid to the gut health of the patients with a helminth infection during clinical patient care.

Modulation of microRNAs and claudin-7 in Caco-2 cell line treated with Blastocystis sp., subtype 3 soluble total antigen

Background

Blastocystis sp., is a eukaryote of the large intestine, which is reported from almost all countries. The pathogenesis of this protist is not clear. The current study aimed to analyze the effects of Blastocystis sp., ST3 soluble total antigen (B3STA) on the microRNAs (miRNAs) involved in the gut permeability and also pro-inflammatory cytokines, occludin, and claudin-7.

Methods

Blastocystis sp., ST3 isolated from stool sample was purified, and its soluble total antigen was extracted using freeze and thawing. The Caco-2 cell line was treated with B3STA for 24 h and the expression levels of mir-16, mir-21, mir-29a, mir-223, and mir-874 were analyzed. In addition, the expression levels of il-8, il-15, occludin, and claudin-7 genes were assessed.

Results

B3STA significantly upregulated the expression of mir-223, and mir-874, and downregulated mir-29a. The expression of mir-16 and mir-21 was not significant. In addition, the expression of il-8 and il-15 was not significant. B3STA significantly decreased the expression level of claudin-7 (P-value < 0.0001), but the expression of occludin was not significant. Our results showed significant correlation between all studied miRNAs, except mir-29a, with downregulation of claudin-7.

Conclusions

This is the first study investigating the effects of Blastocystis sp., ST3 isolated from symptomatic subjects on the expression levels of miRNAs involved in the gut permeability. Our results demonstrated that B3STA may change miRNA expression, which are involved in the gut barrier integrity, and downregulates claudin-7, which is known as sealing factor.

Anti-blastocystosis activity of antioxidant coated ZIF-8 combined with mesoporous silicas MCM-41 and KIT-6

The biocompatible hybrid Zeolitic imidazolate framework-8 (ZIF-8)/structured silica nanocomposite can be loaded with antioxidants such as curcumin and resveratrol to offer multiple advantages of drug functionalization and structural stability. blastocystosis, an enteric parasite, has various outcomes and its treatment includes drugs which have side effects and do not result in a full cure. We aimed to design novel biocompatible nanocomposites containing natural antioxidant, resveratrol or curcumin and ZIF-8/mesoporous silica. We also assessed their anti-blastocystosis activities as bioactive novel nanocomposites. The nano-silica (MCM-41 and KIT-6) was synthesized using a hydrothermal technique and made composite with ZIF-8 using an ultrasonic technique. The antioxidants, curcumin and resveratrol, were loaded over ZIF-8/MCM-41 and ZIF-8/KIT-6 using a rotary evaporator technique to form novel nanocomposites with bioactive properties. The formulated nanocomposites were characterized. To test their biological activity, suspension of cultured blastocystosis cysts (subtype 3) were exposed to increasing concentrations of nanocomposites and the minimal lethal concentration of each nanocomposite was calculated. The bioactive nanocomposites (ZIF-8/KIT-6, ZIF-8/KIT-6/Resveratrol and ZIF-8/MCM-41/Curcumin) were formulated. Anti-blastocystosis activity of the tested nanocomposites was both dose and time dependent. ZIF-8/KIT-6/Resveratol showed the maximum percentage of growth inhibition (~ 100%) at a concentration of 500 µg/ml after 5 h of exposure. More than 90% of blastocystosis cysts’ growth was significantly inhibited at all concentrations of ZIF-8/MCM-41/Curcumin, with different times of exposure, while it occurred only at the highest concentration of ZIF-8/KIT-6 (800 µg/ml). Using cheap, simple, reproducible and scalable techniques, we nano-formulated innovative bioactive nanocomposites, by incorporating the bioactive ZIF-8 (Zn²⁺ with imidazole), structured mesosilica and natural antioxidant compounds, curcumin or resveratrol, to generate multifunctional modalities. These eco-friendly, naturally based, safe, economical, biocompatible, and bioavailable nanocomposites are potential nanotherapeutics. The anti-blastocystosis results of these three nanocomposites indicate their potentially promising innovative and safe use as alternative Blastocystosis therapies.